transponder

noun

tran·​spon·​der tran(t)-ˈspän-dər How to pronounce transponder (audio)
: a radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals

Did you know?

This word was coined during World War II by simply joining pieces of the words transmitter and responder. Transponders are basic to modern aviation and communications satellites, and they're finding new uses in fields such as medicine as well. But they're now also part of everyday life. The "E-ZPass" that lets you drive right through turnpike tollbooths is a transponder, and the car you're driving may not even start unless it recognizes the signal from your personal key's transponder. In a big crowded foot race, you may carry a tiny transponder on your shoe that records when you cross both the starting line and the finish line.

Examples of transponder in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Maritime tracking services using a combination of transponder data and satellite imagery have reported a significant decline in the number of vessels trying to navigate the waters. — David Goldman, CNN Money, 17 Aug. 2026 The Secretary added that his numbers also include tankers which had transited the Strait of Hormuz with their lights and transponders turned off, keeping them hidden from the Iranian Revolutionary Guard Corps (IRGC) and tracking satellites. — David Blackmon, Forbes.com, 12 Aug. 2026 Air Force One, despite the president not being on board, according to the Post, had its transponder turned off. — Katherine Faulders, ABC News, 11 Aug. 2026 The data can be collected by smartphone apps, transponders and other technology, with the apps able to detect whether a driver is handling the phone and is distracted — a leading cause of accidents along with speeding. — Los Angeles Times, 20 July 2026 See All Example Sentences for transponder

Word History

Etymology

transmitter + responder

First Known Use

circa 1944, in the meaning defined above

Time Traveler
The first known use of transponder was circa 1944

Rhymes for transponder

See All Rhymes for transponder

Browse Nearby Words

transpolar
transponder
transpontine
See all Nearby Words

Cite this Entry

“Transponder.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/transponder. Accessed 23 Aug. 2026.

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More from Merriam-Webster on transponder

Nglish: Translation of transponder for Spanish Speakers

Britannica.com: Encyclopedia article about transponder

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